For many industrial processes that use starches as starting materials, it is desirable to have amylolytic enzymes that can function under high temperature to rapidly breakdown starch to release smaller carbohydrates, resulting in a reduction in viscosity. The more the viscosity drops, the more access such enzyme have to further cleave the starch, and the less mechanical power is required for mixing the reaction. A number of enzymes are useful for starch liquefaction, including the α-amylases from Bacillus lichenformis or Geobacillus stearothermophilus, AmyL and AmyS respectively, which are well-suited for liquefaction of starches at high temperature.
Generally, enzymes must be added to a liquefaction process in sufficient amounts to provide accomplish the objective, i.e., there must be sufficient enzyme activity (or catalytic activity) to liquefy the starch substrate within a preselected time-frame. Enzyme activity can be measured per unit of enzyme, and is called specific activity. Thus, an enzyme with lower specific activity must be used in greater amounts to provide a desired amount of enzyme activity in a given process. It is often advantageous to be able to make high specific activity enzyme preparations, allowing the use of a smaller amount to produce a desired effect. This can be accomplished, for example, by purifying a crude enzyme preparation. However, even a pure enzyme has a maximum specific activity for a given substrate under particular assay conditions.
The need exists for improved α-amylases that are suited for liquefaction of starches at high temperature.